Conventional machine tools for electrical discharge machining, electrochemical machining or like operations, such as disclosed in my earlier U.S. Pat. No. 3,859,003, provide improved axial stability of a ram with respect to an outer ram support over earlier precision heads. However the costs associated with manufacturing such heads is substantial because of the raceway construction for receiving ball bearings which support the ram for axial movement within the outer ram support.
Also, in my two raceway embodiment, the ram when fully extended has been detected to deflect in a transverse direction to the plane extending through the two raceways. My four raceway embodiment is costly to manufacture and it is difficult to maintain alignment along the axial length of ram travel because of the four corner support.